resolving merge conflicts

examples/run_squad.py

@@ -46,7 +46,10 @@ logger = logging.getLogger(__name__)
 
 
 class SquadExample(object):
-    """A single training/test example for the Squad dataset."""
+    """
+    A single training/test example for the Squad dataset.
+    For examples without an answer, the start and end position are -1.
+    """
 
     def __init__(self,
                  qas_id,
@@ -54,13 +57,15 @@ class SquadExample(object):
                  doc_tokens,
                  orig_answer_text=None,
                  start_position=None,
-                 end_position=None):
+                 end_position=None,
+                 is_impossible=None):
         self.qas_id = qas_id
         self.question_text = question_text
         self.doc_tokens = doc_tokens
         self.orig_answer_text = orig_answer_text
         self.start_position = start_position
         self.end_position = end_position
+        self.is_impossible = is_impossible
 
     def __str__(self):
         return self.__repr__()
@@ -75,6 +80,8 @@ class SquadExample(object):
             s += ", start_position: %d" % (self.start_position)
         if self.start_position:
             s += ", end_position: %d" % (self.end_position)
+        if self.start_position:
+            s += ", is_impossible: %r" % (self.is_impossible)
         return s
 
 
@@ -92,7 +99,8 @@ class InputFeatures(object):
                  input_mask,
                  segment_ids,
                  start_position=None,
-                 end_position=None):
+                 end_position=None,
+                 is_impossible=None):
         self.unique_id = unique_id
         self.example_index = example_index
         self.doc_span_index = doc_span_index
@@ -104,9 +112,10 @@ class InputFeatures(object):
         self.segment_ids = segment_ids
         self.start_position = start_position
         self.end_position = end_position
+        self.is_impossible = is_impossible
 
 
-def read_squad_examples(input_file, is_training):
+def read_squad_examples(input_file, is_training, version_2_with_negative):
     """Read a SQuAD json file into a list of SquadExample."""
     with open(input_file, "r", encoding='utf-8') as reader:
         input_data = json.load(reader)["data"]
@@ -140,10 +149,14 @@ def read_squad_examples(input_file, is_training):
                 start_position = None
                 end_position = None
                 orig_answer_text = None
+                is_impossible = False
                 if is_training:
-                    if len(qa["answers"]) != 1:
+                    if version_2_with_negative:
+                        is_impossible = qa["is_impossible"]
+                    if (len(qa["answers"]) != 1) and (not is_impossible):
                         raise ValueError(
                             "For training, each question should have exactly 1 answer.")
+                    if not is_impossible:
                         answer = qa["answers"][0]
                         orig_answer_text = answer["text"]
                         answer_offset = answer["answer_start"]
@@ -163,6 +176,10 @@ def read_squad_examples(input_file, is_training):
                             logger.warning("Could not find answer: '%s' vs. '%s'",
                                            actual_text, cleaned_answer_text)
                             continue
+                    else:
+                        start_position = -1
+                        end_position = -1
+                        orig_answer_text = ""
 
                 example = SquadExample(
                     qas_id=qas_id,
@@ -170,7 +187,8 @@ def read_squad_examples(input_file, is_training):
                     doc_tokens=doc_tokens,
                     orig_answer_text=orig_answer_text,
                     start_position=start_position,
-                    end_position=end_position)
+                    end_position=end_position,
+                    is_impossible=is_impossible)
                 examples.append(example)
     return examples
 
@@ -200,7 +218,10 @@ def convert_examples_to_features(examples, tokenizer, max_seq_length,
 
         tok_start_position = None
         tok_end_position = None
-        if is_training:
+        if is_training and example.is_impossible:
+            tok_start_position = -1
+            tok_end_position = -1
+        if is_training and not example.is_impossible:
             tok_start_position = orig_to_tok_index[example.start_position]
             if example.end_position < len(example.doc_tokens) - 1:
                 tok_end_position = orig_to_tok_index[example.end_position + 1] - 1
@@ -272,20 +293,25 @@ def convert_examples_to_features(examples, tokenizer, max_seq_length,
 
             start_position = None
             end_position = None
-            if is_training:
+            if is_training and not example.is_impossible:
                 # For training, if our document chunk does not contain an annotation
                 # we throw it out, since there is nothing to predict.
                 doc_start = doc_span.start
                 doc_end = doc_span.start + doc_span.length - 1
-                if (example.start_position < doc_start or
+                out_of_span = False
-                        example.end_position < doc_start or
+                if not (tok_start_position >= doc_start and
-                        example.start_position > doc_end or example.end_position > doc_end):
+                        tok_end_position <= doc_end):
-                    continue
+                    out_of_span = True
-
+                if out_of_span:
+                    start_position = 0
+                    end_position = 0
+                else:
                     doc_offset = len(query_tokens) + 2
                     start_position = tok_start_position - doc_start + doc_offset
                     end_position = tok_end_position - doc_start + doc_offset
-
+            if is_training and example.is_impossible:
+                start_position = 0
+                end_position = 0
             if example_index < 20:
                 logger.info("*** Example ***")
                 logger.info("unique_id: %s" % (unique_id))
@@ -302,7 +328,9 @@ def convert_examples_to_features(examples, tokenizer, max_seq_length,
                     "input_mask: %s" % " ".join([str(x) for x in input_mask]))
                 logger.info(
                     "segment_ids: %s" % " ".join([str(x) for x in segment_ids]))
-                if is_training:
+                if is_training and example.is_impossible:
+                    logger.info("impossible example")
+                if is_training and not example.is_impossible:
                     answer_text = " ".join(tokens[start_position:(end_position + 1)])
                     logger.info("start_position: %d" % (start_position))
                     logger.info("end_position: %d" % (end_position))
@@ -321,7 +349,8 @@ def convert_examples_to_features(examples, tokenizer, max_seq_length,
                     input_mask=input_mask,
                     segment_ids=segment_ids,
                     start_position=start_position,
-                    end_position=end_position))
+                    end_position=end_position,
+                    is_impossible=example.is_impossible))
             unique_id += 1
 
     return features
@@ -401,15 +430,15 @@ def _check_is_max_context(doc_spans, cur_span_index, position):
     return cur_span_index == best_span_index
 
 
-
 RawResult = collections.namedtuple("RawResult",
                                    ["unique_id", "start_logits", "end_logits"])
 
 
 def write_predictions(all_examples, all_features, all_results, n_best_size,
                       max_answer_length, do_lower_case, output_prediction_file,
-                      output_nbest_file, verbose_logging):
+                      output_nbest_file, output_null_log_odds_file, verbose_logging,
-    """Write final predictions to the json file."""
+                      version_2_with_negative, null_score_diff_threshold):
+    """Write final predictions to the json file and log-odds of null if needed."""
     logger.info("Writing predictions to: %s" % (output_prediction_file))
     logger.info("Writing nbest to: %s" % (output_nbest_file))
 
@@ -427,15 +456,29 @@ def write_predictions(all_examples, all_features, all_results, n_best_size,
 
     all_predictions = collections.OrderedDict()
     all_nbest_json = collections.OrderedDict()
+    scores_diff_json = collections.OrderedDict()
+
     for (example_index, example) in enumerate(all_examples):
         features = example_index_to_features[example_index]
 
         prelim_predictions = []
+        # keep track of the minimum score of null start+end of position 0
+        score_null = 1000000  # large and positive
+        min_null_feature_index = 0  # the paragraph slice with min mull score
+        null_start_logit = 0  # the start logit at the slice with min null score
+        null_end_logit = 0  # the end logit at the slice with min null score
         for (feature_index, feature) in enumerate(features):
             result = unique_id_to_result[feature.unique_id]
-
             start_indexes = _get_best_indexes(result.start_logits, n_best_size)
             end_indexes = _get_best_indexes(result.end_logits, n_best_size)
+            # if we could have irrelevant answers, get the min score of irrelevant
+            if version_2_with_negative:
+                feature_null_score = result.start_logits[0] + result.end_logits[0]
+                if feature_null_score < score_null:
+                    score_null = feature_null_score
+                    min_null_feature_index = feature_index
+                    null_start_logit = result.start_logits[0]
+                    null_end_logit = result.end_logits[0]
             for start_index in start_indexes:
                 for end_index in end_indexes:
                     # We could hypothetically create invalid predictions, e.g., predict
@@ -463,7 +506,14 @@ def write_predictions(all_examples, all_features, all_results, n_best_size,
                             end_index=end_index,
                             start_logit=result.start_logits[start_index],
                             end_logit=result.end_logits[end_index]))
-
+        if version_2_with_negative:
+            prelim_predictions.append(
+                _PrelimPrediction(
+                    feature_index=min_null_feature_index,
+                    start_index=0,
+                    end_index=0,
+                    start_logit=null_start_logit,
+                    end_logit=null_end_logit))
         prelim_predictions = sorted(
             prelim_predictions,
             key=lambda x: (x.start_logit + x.end_logit),
@@ -478,7 +528,7 @@ def write_predictions(all_examples, all_features, all_results, n_best_size,
             if len(nbest) >= n_best_size:
                 break
             feature = features[pred.feature_index]
-
+            if pred.start_index > 0:  # this is a non-null prediction
                 tok_tokens = feature.tokens[pred.start_index:(pred.end_index + 1)]
                 orig_doc_start = feature.token_to_orig_map[pred.start_index]
                 orig_doc_end = feature.token_to_orig_map[pred.end_index]
@@ -499,12 +549,23 @@ def write_predictions(all_examples, all_features, all_results, n_best_size,
                     continue
 
                 seen_predictions[final_text] = True
+            else:
+                final_text = ""
+                seen_predictions[final_text] = True
+
             nbest.append(
                 _NbestPrediction(
                     text=final_text,
                     start_logit=pred.start_logit,
                     end_logit=pred.end_logit))
-
+        # if we didn't include the empty option in the n-best, include it
+        if version_2_with_negative:
+            if "" not in seen_predictions:
+                nbest.append(
+                    _NbestPrediction(
+                        text="",
+                        start_logit=null_start_logit,
+                        end_logit=null_end_logit))
         # In very rare edge cases we could have no valid predictions. So we
         # just create a nonce prediction in this case to avoid failure.
         if not nbest:
@@ -514,8 +575,12 @@ def write_predictions(all_examples, all_features, all_results, n_best_size,
         assert len(nbest) >= 1
 
         total_scores = []
+        best_non_null_entry = None
         for entry in nbest:
             total_scores.append(entry.start_logit + entry.end_logit)
+            if not best_non_null_entry:
+                if entry.text:
+                    best_non_null_entry = entry
 
         probs = _compute_softmax(total_scores)
 
@@ -530,7 +595,17 @@ def write_predictions(all_examples, all_features, all_results, n_best_size,
 
         assert len(nbest_json) >= 1
 
+        if not version_2_with_negative:
             all_predictions[example.qas_id] = nbest_json[0]["text"]
+        else:
+            # predict "" iff the null score - the score of best non-null > threshold
+            score_diff = score_null - best_non_null_entry.start_logit - (
+                best_non_null_entry.end_logit)
+            scores_diff_json[example.qas_id] = score_diff
+            if score_diff > null_score_diff_threshold:
+                all_predictions[example.qas_id] = ""
+            else:
+                all_predictions[example.qas_id] = best_non_null_entry.text
                 all_nbest_json[example.qas_id] = nbest_json
 
     with open(output_prediction_file, "w") as writer:
@@ -539,6 +614,10 @@ def write_predictions(all_examples, all_features, all_results, n_best_size,
     with open(output_nbest_file, "w") as writer:
         writer.write(json.dumps(all_nbest_json, indent=4) + "\n")
 
+    if version_2_with_negative:
+        with open(output_null_log_odds_file, "w") as writer:
+            writer.write(json.dumps(scores_diff_json, indent=4) + "\n")
+
 
 def get_final_text(pred_text, orig_text, do_lower_case, verbose_logging=False):
     """Project the tokenized prediction back to the original text."""
@@ -701,7 +780,7 @@ def main():
     parser.add_argument("--num_train_epochs", default=3.0, type=float,
                         help="Total number of training epochs to perform.")
     parser.add_argument("--warmup_proportion", default=0.1, type=float,
-                        help="Proportion of training to perform linear learning rate warmup for. E.g., 0.1 = 10% "
+                        help="Proportion of training to perform linear learning rate warmup for. E.g., 0.1 = 10%% "
                              "of training.")
     parser.add_argument("--n_best_size", default=20, type=int,
                         help="The total number of n-best predictions to generate in the nbest_predictions.json "
@@ -738,7 +817,12 @@ def main():
                         help="Loss scaling to improve fp16 numeric stability. Only used when fp16 set to True.\n"
                              "0 (default value): dynamic loss scaling.\n"
                              "Positive power of 2: static loss scaling value.\n")
-
+    parser.add_argument('--version_2_with_negative',
+                        action='store_true',
+                        help='If true, the SQuAD examples contain some that do not have an answer.')
+    parser.add_argument('--null_score_diff_threshold',
+                        type=float, default=0.0,
+                        help="If null_score - best_non_null is greater than the threshold predict null.")
     args = parser.parse_args()
 
     if args.local_rank == -1 or args.no_cuda:
@@ -787,9 +871,9 @@ def main():
     num_train_optimization_steps = None
     if args.do_train:
         train_examples = read_squad_examples(
-            input_file=args.train_file, is_training=True)
+            input_file=args.train_file, is_training=True, version_2_with_negative=args.version_2_with_negative)
         num_train_optimization_steps = int(
-            len(train_examples) / args.train_batch_size / args.gradient_accumulation_steps) * args.num_train_epochs
+            len(train_dataset) / args.train_batch_size / args.gradient_accumulation_steps) * args.num_train_epochs
         if args.local_rank != -1:
             num_train_optimization_steps = num_train_optimization_steps // torch.distributed.get_world_size()
 
@@ -825,7 +909,7 @@ def main():
 
     if args.fp16:
         try:
-            from apex.optimizers import FP16_Optimizer
+            from apex.optimizer import FP16_Optimizer
             from apex.optimizers import FusedAdam
         except ImportError:
             raise ImportError("Please install apex from https://www.github.com/nvidia/apex to use distributed and fp16 training.")
@@ -901,7 +985,7 @@ def main():
                 if (step + 1) % args.gradient_accumulation_steps == 0:
                     if args.fp16:
                         # modify learning rate with special warm up BERT uses
-                        # if args.fp16 is False, BertAdam is used that handles this automatically
+                        # if args.fp16 is False, BertAdam is used and handles this automatically
                         lr_this_step = args.learning_rate * warmup_linear(global_step/num_train_optimization_steps, args.warmup_proportion)
                         for param_group in optimizer.param_groups:
                             param_group['lr'] = lr_this_step
@@ -914,7 +998,6 @@ def main():
     output_model_file = os.path.join(args.output_dir, "pytorch_model.bin")
     if args.do_train:
         torch.save(model_to_save.state_dict(), output_model_file)
-
         # Load a trained model that you have fine-tuned
         model_state_dict = torch.load(output_model_file)
         model = BertForQuestionAnswering.from_pretrained(args.bert_model, state_dict=model_state_dict)
@@ -925,7 +1008,7 @@ def main():
 
     if args.do_predict and (args.local_rank == -1 or torch.distributed.get_rank() == 0):
         eval_examples = read_squad_examples(
-            input_file=args.predict_file, is_training=False)
+            input_file=args.predict_file, is_training=False, version_2_with_negative=args.version_2_with_negative)
         eval_features = convert_examples_to_features(
             examples=eval_examples,
             tokenizer=tokenizer,
@@ -969,10 +1052,12 @@ def main():
                                              end_logits=end_logits))
         output_prediction_file = os.path.join(args.output_dir, "predictions.json")
         output_nbest_file = os.path.join(args.output_dir, "nbest_predictions.json")
+        output_null_log_odds_file = os.path.join(args.output_dir, "null_odds.json")
         write_predictions(eval_examples, eval_features, all_results,
                           args.n_best_size, args.max_answer_length,
                           args.do_lower_case, output_prediction_file,
-                          output_nbest_file, args.verbose_logging)
+                          output_nbest_file, output_null_log_odds_file, args.verbose_logging,
+                          args.version_2_with_negative, args.null_score_diff_threshold)
 
 
 if __name__ == "__main__":